The main difference between solid-state fermentation and submerged fermentation is that solid-state fermentation takes place on a solid substrate with minimal or no free-flowing liquid, whereas submerged fermentation occurs in a liquid medium where the microorganisms are submerged.
Solid-state fermentation and submerged fermentation are two distinct methods in industrial bioprocessing to produce various products such as enzymes, pharmaceuticals, biofuels, and organic acids. Both techniques involve the cultivation of microorganisms. They differ in terms of the growth medium and the physical state of fermentation.
Key Areas Covered
1. What is Solid-state Fermentation
– Definition, Moisture Content, Oxygen Availability
2. What is Submerged Fermentation
– Definition, Moisture Content, Oxygen Availability
3. Similarities Between Solid-state Fermentation and Submerged Fermentation
– Common Features
4. Difference Between Solid-state Fermentation and Submerged Fermentation
– Comparison of Key Differences
Key Terms
Solid-state Fermentation, Submerged Fermentation
What is Solid-state Fermentation
Solid-state fermentation is a bioprocess that involves the cultivation of microorganisms on a solid substrate in the absence or with limited amounts of free water. It is a versatile and environmentally friendly technology used in the production of a wide range of products, including enzymes, biofuels, organic acids, pharmaceuticals, and fermented foods.
Solid-state fermentation relies on the utilization of solid substrates, which can be natural materials such as agricultural residues, agro-industrial byproducts, or synthetic materials. These substrates provide a solid matrix for microbial growth and serve as a source of nutrients for the microorganisms.
The moisture content in solid-state fermentation is relatively low than other fermentation techniques. Generally, solid-state fermentation involves low moisture content (around 20-70 percent of the substrate weight), limiting the availability of free water. Microorganisms obtain moisture from the substrate or through metabolic processes.
Another characteristic of solid-state fermentation is the limited oxygen availability. Due to the solid nature of the substrate, oxygen diffusion is restricted, resulting in oxygen gradients within the fermentation system. The outer layers of the substrate are exposed to oxygen, while the inner layers have reduced oxygen availability. Furthermore, the advantages of solid-state fermentation include its cost-effectiveness, product yield, and specificity.
What is Submerged Fermentation
Submerged fermentation is a widely used bioprocessing technique in which microorganisms are cultivated in a liquid medium. In submerged fermentation, microorganisms are submerged in a liquid growth medium containing water, nutrients, and other essential components for microbial growth. The liquid medium provides a homogenous environment that allows better control over parameters like pH, temperature, oxygenation, and nutrient availability.
One advantage of submerged fermentation is its scalability. The use of liquid media enables the cultivation of microorganisms in large-scale bioreactors, ranging from laboratory-scale to industrial-scale operations. Another advantage of submerged fermentation is the efficient oxygen supply. Continuous stirring or aeration in submerged fermentation ensures sufficient oxygenation throughout the liquid medium, providing an oxygen-rich environment for microorganisms. Proper oxygenation is essential for aerobic microorganisms because it promotes their growth, metabolism and the production of desired metabolites.
This efficient oxygen transfer in submerged fermentation results in higher biomass yields and increased productivity compared to other fermentation techniques. Submerged fermentation offers better mixing and nutrient distribution. Moreover, continuous stirring or agitation in submerged fermentation maintains a uniform distribution of nutrients, oxygen, and microbial cells in the liquid medium.
The liquid nature of submerged fermentation allows for easy monitoring and control of fermentation parameters like pH, temperature, dissolved oxygen levels, and other variables. These can be monitored and adjusted in real-time to optimize microbial growth and product formation.
Similarities Between Solid-state Fermentation and Submerged Fermentation
- Solid-state fermentation and submerged fermentation are two methods useful in industrial bioprocessing.
- Both methods involve the cultivation of microorganisms.
Difference Between Solid-state Fermentation and Submerged Fermentation
Definition
Solid-state fermentation takes place on a solid substrate with minimal or no free-flowing liquid, whereas submerged fermentation occurs in a liquid medium where microorganisms are submerged.
Moisture Content
Solid-state fermentation involves a lower moisture content than submerged fermentation.
Oxygen Availability
The oxygen supply in solid-state fermentation is limited, whereas, in submerged fermentation, oxygen is readily available.
Conclusion
Solid-state fermentation and submerged fermentation are two distinct methods useful in industrial bioprocessing to produce various products such as enzymes, pharmaceuticals, biofuels, and organic acids. The main difference between solid-state fermentation and submerged fermentation is that solid-state fermentation takes place on a solid substrate with minimal or no free-flowing liquid, whereas submerged fermentation occurs in a liquid medium with microorganisms.
Reference:
1. “Solid State Fermentation – Overview.” Science Direct.
2. “Submerged Fermentation – Overview.” Science Direct.
Image Courtesy:
1. “Dry – solid-state anaerobic digestion AD biogas plant” By Thzorro77 – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Submerged Fermentation” By Albert Paul 1840719 – Own work (CC BY-SA 4.0) via Commons Wikimedia
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